The present invention relates to an apparatus for mounting electronic parts of surface-mounted type onto a printed board and, more particularly, relates to a type of apparatus for mounting electronic parts, which can mount various kinds of electronic parts different in size from each other and which can operate at high speed.
A conventional type electronic-part mounting apparatus has a plurality of suction heads which are arranged along a peripheral portion of an index table rotating intermittently in a fixed direction. Each suction head is provided with a vacuum suction nozzle. Each electronic part supplied to a suction station by a part-feeder is attracted by suction on a corresponding one of the suction nozzles at the suction station. The electronic part attracted on the forward end of the suction nozzle is moved with intermittent rotation of the index table, and is adjusted to its correct position and direction by an adjusting and positioning means (hereinafter also referred also to as "positioner") arranged on a path along which the suction nozzles move. Then, the electronic part is brought to a mounting station where the part is released from the suction nozzle and is mounted onto a printed board. Subsequently, the suction head again returns to the suction station with the index table rotating in the fixed direction, and repeats the above operation. A conventional electronic part mounting apparatus has as disclosed in Japanese Unexamined Patent Publication No. 61-179595, only one adjusting-positioning means (positioner) for adjusting the electronic part to its correct position and direction, so that the apparatus cannot mount various kinds of electronic parts largely different in configuration and size from each other.
In order to overcome the above-mentioned drawback, a new type electronic-part mounting apparatus including at least two positioners has been developed in recent years. FIG. 3 of the accompanying drawings is a diagrammatic top plan view of the electronic-part mounting apparatus which includes two positioners. An index table 2 is provided at its peripheral portion with a plurality of suction heads 6 and is rotated intermittently in a fixed direction indicated by an arrow. An electronic part in the form of a chip component is attracted by suction onto the suction head 6 from a part feeder table 1 which shifts along its longitudinal axis from side to side. With the intermittent rotation of the index table 2 in the direction indicated by the arrow, the electronic part attracted on the suction head 6 is moved onto either one of two positioners 3a and 3b for adjusting the electronic part to its correct position and direction. Either of the two positioners 3a and 3b is selected according to the configuration and size of the part and one of them is used. The part adjusted to its correct position and direction is transported with rotation of the index table 2, and the state of the attracted part is checked by a detector 4. Subsequently, the part is mounted onto the printed board 5 which is positioned with a positioning table movable in X and Y directions.
FIGS. 4A and 4B are respectively side elevational and plan views illustrating the positioner 3a or 3b. Four adjusting claws 13a through 13d are guided in respective guides 14a through 14d which are fixed on a disk 11 and whose longitudinal axes make a right-angled cross form. The disc 11 is rotated and stands still at a desired angle according to the direction of the part. One of the vacuum nozzles 12 of the suction heads 6 mounted on the index table 2 is lowered so that the electronic part 9 attracted on the forward ends of the vacuum nozzle 12 is set among the forward ends of the adjusting claws 13a through 13d. These four adjusting claws move forward along the respective axes and push the part 9 to adjust the part 9 to its correct position and direction. Subsequently, the nozzle 12 holding the part 9 by suction is again raised. Each of the two positioners 3a and 3b has its structure as shown in FIGS. 4A and 4B, but they are different from each other in the size of the adjusting claws and in the size of the space surrounded by the adjusting claws when they are closed, so that various kinds of electronic parts largely different in configuration and size from each other can be adjusted. When one of the two positioners 3a and 3b is selected according to the configuration and size of the part retained by the nozzle 12, the nozzle 12 stands still above that selected positioner and is lowered thereto. But, above the positioner not to be selected, the nozzle 12 passes away without lowering.
Since, in the above-described prior art, the positioners and the detector are arranged at a half side of the index table 2, the diameter of the index table increases. As a result, the accuracy on mounting the electronic parts to the nozzle deteriorates, and the situation of the part attracted on the forward end of the suction head is apt to be changed by the centrifugal force increased in proportion to the diameter of the index table. In order to prevent these, it is required to reduce the mean rotational speed of the index table, and it results in reduction of the productivity. In order to prevent such reduction in the productivity, it is required to increase a number of the suction heads mounted on the index table, so that a capacity of a driving source for intermittent rotation of the index table increases. Thus, the apparatus according to the prior art has various disadvantages regarding an increase in operational speed, a reduction in size and a reduction in cost.